In the field of construction machines such as a hydraulic shovel, in order to prevent engine trouble, undesirable exhaust emissions and others due to the use of inadequate fuel, there has been known a device for detecting a property (physical property such as kinetic viscosity or density, or chemical property) of fuel to be supplied to an engine.
For example, the following Patent Document 1 discloses a device comprising a fuel tank for storing fuel, and a density sensor provided at a bottom of the fuel tank, in adjacent relation to an inlet of a suction pipe of the fuel tank, wherein the density sensor is operable to detect a density of fuel to be sucked into the suction pipe (conventional technique 1).
The Patent Document 2 discloses a device comprising: a small chamber which is defined in an upper region of an internal space of a fuel tank at a position facing a fuel filler opening, and formed with an inlet and an outlet; and a sensor capable of detecting a property of a part of fed fuel which stagnates in a bottom region of the small chamber (conventional technique 2).
However, in each of the conventional techniques 1 and 2, the sensor and associated structure are installed to the fuel tank itself. Thus, each of the conventional techniques 1 and 2 cannot be added on (added as an aftermarket option) to an existing construction machine, unless a fuel tank therein is subjected to significant modification or replacement.
Moreover, in the conventional technique 1, the sensor and associated structure protrude from a bottom surface of the fuel tank to the outside. Thus, due to a fuel tank installation space, interference with other devices, etc., layout flexibility during mounting on a construction machine will be deteriorated.
As a solution to such a problem, it is conceivable to detect a fuel property in the course of a fuel supply pipeline connecting a fuel tank and an engine, by a sensor provided in the course of the fuel supply pipeline (hereinafter referred to as “in-pipeline detection system”).
Based on employing the in-pipeline detection system, it becomes possible to add on the sensor and associated structure to a construction machine without carrying out modification or replacement of a fuel tank itself. Moreover layout flexibility for mounting the sensor and associated structure to the construction machine is high.
However, in the in-pipeline detection system, it is necessary to detect a property of fuel which is flowing through the pipeline at a high flow velocity. Thus, due to difficulty in ensuring a time required for the fuel property detection, and a large variation in flow velocity and flow quantity of fuel, accuracy and stability of the detection becomes deteriorated.